The understandable notes - ELECTRICITY, Class 10, Part-5
HEATING EFFECT OF ELECTRIC CURRENT
When electricty is supplied to appliances then some of the electricity is used for useful purposes like rotating the blades of the fan but it doesn't utilize all the electricity. We all know that electricity is a form of energy and energy can neither be creater nor destroyed but it only transforms its form. So when the energy which is supplied is more than consumed than the rest of the energy is transformed into heat energy.This is called heating effect of electric current. It is understandable that higher the resistance of the circuit, greater the heating effect. Because resistance is the obstruction in the flow of charges and this obstruction forces electricity to convert to heat energy. Just imagine if the circuit is completely resistive in nature. Means all the energy will transform to heat energy and we are using these circuits currently in many appliances like coil heater, electric iron, immersion rods all are equipped with those circuits which are highly resistive.
The heating effect of electric current refers to the phenomenon where electrical energy is converted into heat energy when current flows through a conductor due to its resistance.
(Jab hum apne ghar ke fan ko bahut der tak continuosly use kte ho tab aapne kabhi notice kiya ki vo fan garam ho jata hai. Same chiz aapke aur bhi appliances kai sath bhi hoti hai. Ab dekho yaar hum kehte to hai ki cooper, iron yani ki metals electricity ke conductors hote hai par resistivity to inki bhi hoti hai na. Resistance to ye bhi possess krte hi hai. Agar koi object jo ki 100 percent electricty ko apne andar se paas krwa de to fir wo heat nhi hoga. Aur agar aap soch rhe ho ki aisa to koi material hi nhi hota to pesh hai aapke saamne superconductors. Inki resistance zero hoti hai. Yani ki inme se jab electricity conduct krwayi jati hai tab ye heat nhi honge. Baki generally sare conductors heat up ho hi jate hai. Vaise itna book mai nhi likha bas knowledgeke liye padh lo. Ab dekho pehle part mai maine kaha tha ki bijli ek prakar ki urja hai. Haan to energy ka ek rule hota hai ki ye kisi ki bhi nhi sunti matlab ye na to kabhi create ho sakti hai na hi kabhi destroy ho sakti. Ise samajhne ke liye aap kai examples le sakte ho. Jaise ki jab thermal power plant mai coal ko burn krke bijli banayi jati hai tab coal se jo thermal energy bani usne baad me electrical energy ka roop le liya. Aur jo samajhdar soch rhe hai ki coal ko jalakar energy create hui hai to aisa mat socho kyonki theory of relativity ke hisab se maas bhi ek kind ki energy hoti hai. Itna isliye likh rha hu ki thodi extra knowledge bhi honi chahiye. To haan hum kaha the ki jab kisi upkaran yani appliance mai electricty ka supply hota hai aur agar vo sari energy ko consume nhi kar pata jo ki generally cases mai hota hi hai to rest of the energy heat energy mai convert ho jati hai. Ab iska simple sa reason hai resistance. Dekho generally resistance ka kaam kya hai, current ke flow ma taang adana. Ab iska result ye nikalkar aata hai ki jab current pura flow nhi ho rha to vo energy jo battery de rhi hai charges ke flow ke liye wo gayi kaha. Yaar potential ek tarike ka work hai aur work aur energy ki unit same hi to hai joule. To ham keh sakte hai ko jo energy battery supply krti hai electrons ke flow ke liye usi energy ka pura use na ho pane kai karan ye heating effect banta hai. Ab jin circuits mai resistance high hogi unme ye heating effect bhi jyada hoga aur iski wajah se ye kai jagah par use bhi kiya jata hai. Baki last mai ek proper definition bhi likh di ai se uthakar agar 1 number mai aaye to likh aana.)
JOULE'S LAW OF HEATING
Joule's Law of Heating states that the amount of heat produced in a conductor due to the flow of electric current is directly proportional to the square of the current, the resistance of the conductor, and the time for which the current flows.
Consider a current I flowing through a resistor.
Let V be the potential difference across it.
Let the magnitude of charge is Q which is flowing during a time period of t.
Now, we all know that potential is work done/charge. So work done is equal to product of potential and charge.
Work done= VQ.
Now if you are bazzled how power equation is converted in heat energy then power is the rate of energy transfer and heat energy is total energy dissipated over time due to resistance. If we multiply the rate to time then we got the required equation
(Ab heating effect ke liye ek law bhi hai jise joules law of heating bolte hai. Ab isme kehte hai ki heat directly proportional hai current ke square ke , resistance ke, aur jitne time kai liye vo flow hua hai uske, yani ki agar current jyada der tak flow hoga to heat energy bhi jyada milegi. Ab aage iski derivation hai vo to yaad hi krni padegi. Haan to humne deeivation ke staring me current ko I mana, Potential difference ko V mana, time ko t mana vagera. Ab ye dekho ki potential hota hai work done divided by charge, to agar potential ko multiply krwa de charge se to work done nhi nikal jayega kya. Ab power ka matlab hota ki rate of doing work. Jaise ki ek kaam krne mai ek aadmi ko 3 ghante lagte hai vhi kaam ek dusra aadmi 2 ghante mai kr de to hum ye kehte hai ki isme power jyada hai. Tension na lo last topic power ka hi hai. Haan to power hoti hai rate of doing work. Ye to pata hi hoga ki work aur energy ki unit same hoti hai joule. To bas rate of doing work ko time se multiply krwa do total energy nikal jayegi. Aur ye equation banegi jo black background mai likhi hai. Ek toh sub and super script ka bhi use nhi ho sakta. )
PRACTICAL APPLICATIONS OF HEATING EFFECT OF ELECTRIC CURRENT
The heating effect of electric current is useful in many appliances like in Electric heater, water geyser, electric iron, hair dryer, toaster, microwave oven, induction cooktop, electric kettle, room heater, soldering iron, coffee maker, sandwich maker, curling iron, straightening iron, electric stove, rice cooker, heat gun, heated blanket, immersion rod, bread maker, convection oven, hot plate.
The electric heating is also used to produce light, as in an electric bulb. Here, the filament must retain as much of the heat generated as is possible, so that it gets very hot and emits light. It must not melt at such high temperature. A strong metal with high melting point such as tungsten (melting point 3380°C) is used for making bulb filaments. The filament should be thermally isolated as much as possible, using insulating support, etc. The bulbs are usually filled with chemically inactive nitrogen and argon gases to prolong the life of filament. Most of the power consumed by the filament appears as heat, but a small part of it is in the form of light radiated.
( Ab dekho jitne bhi aise upkaran hai ko bijli se chalte hai aur unka kaam garam hona ya garam krna hai vo heating effect pr hi kaam krte hai. Isme ek important use hai light kaise banti hai heating effect se. Ab dekho jab kisi filament ek second filament to pata hai na kya hota hai, nhi pata to sun lo ki ek metal ki bahut slim thin wire jiske andar se current paas krwaya jata hai. Ab har metal ki kuch na kuch to resistance hoti hai to usi resistance ki wajah vo metal ek bahut high temperature pr pahuch jata hai. Aur ye koshish kari jati hai ki na to heat bahar ja paye na hi andar aa paye. Further bulb ke andar nitrogen wagera bhari jati hai. Aapne ye to dekha hi hoga ki agar bulb ke upar se kaanch tut jaye to woh filament 1 ya 2 seconds mai hi jal jata hai. Bas isi ko rokne kai liye in gases ka istemaal kiya jata hai. Ab dekho isme ye question bhi aata hai filament kis material ka hota hai aur kyo. To filament tungsten ka hota hai kyonki tungsten ka melting point bahut high hota hai high kya metals mai to highest hota hai. Ab dekho ye filament bahut jyada garam ho jata hai aur fir light emit krne lagta hai. Ye kuch kuch aise hi hai jaise aag ki mashaal but bijli se chalne wali. Ye sari baat jo humne kari vo ek 100 waat kai bubl ki kri hai kahi aap sab socho ki aaj kal to led bulb aa gaye hai to usme filament kaha hota hai. Haan aur energy ka bahut bada part heat mai convert hota hai aur ek chota part light mai.)
One more application of heating effect of electric current. A fuse is a safety device that protects electrical circuits by breaking the flow of current when it exceeds a safe limit. Joule's law, , explains that the heat produced in the fuse wire depends on the current, its resistance, and time. When excessive current flows, the heat generated melts the fuse wire, breaking the circuit and preventing damage to appliances. The fuse material and resistance are chosen to ensure it melts at the desired current limit. Fuse is placed in series with the circuit.
( ab dekho fuse udd gaya iska toh , ye line to bahut suni hogi to chalo iska matlab bhi bata deta hu. Dekho fuse aur kuch nhi ek material ka piece hai jo circuit mai lagaya jata hai series mai, series mai kyo iska jawab comment kr dena chapter khatam hone wala hai. Haan to dekho jab excessive current flow hota hai tab fuse ki material melt hokr circuit break ho jata hai. Ab dekho iska kitna fayda hai ki agar current kam jyada hua to khali fuse kharab hoga nhi to circuit ka konsa part kharab hua ye pata lagana kitna mushkil ho jata. To dekho tumhari book mai to yehi do practical application de rekhi hai to inhe achi tarah padh lo. Dekho concept clear hona chahiye chahe notes se ho, book se ho ya fir video se ho.)
POWER
Rate of doing work is called power.
Power also tells the rate of consumption of energy.
S.I UNIT of power is watt. It is represented by W.
The SI unit of electric power is watt (W). It is the power consumed by
a device that carries 1 A of current when operated at a potential difference
of 1 V. Thus,
1 W = 1 volt × 1 ampere = 1 V A
Now watt is very small unit of power so we generally measure power in kilowaats. One kilowaat means 1000 watts.
One kilowaathour (1KWh) is also the commercial unit of energy consumption.
Now this is also called unit
(Haan to power ki S.I unit hoti hai waat. Ab dekho waat ek bahut choti unit hoti hai isi liye ise kilowaat mai measure krte hai. Ab kilowaat to power hai agar power ko time se multiply kr de to to to yaad kro pichla topic hi to tha total energy nhi nikal jayega kya. Haan to usi energy ko nikalne kai liye kilowaat ko hour se multiply kr diya baad mai inhe S.I unit me tod diya aur ye ho upar nili nili si equation dikh rahi hai na vo nikal aayi. Ab tum isse ye bhi nikal sakte ho ki tumhare ghar mai kon si chiz kitne amount ki bijli use krti hai. Maan lo tumhara A.C 1 ton ka hai matlab uski power hai ek kilowaat. Ab agar din mai vo A.C 6 ghante chala to ek kilowaat ka hone ke karan aur 6 ghamte chalne kai karan vo 6 unit bijli pi jayega. Unit ka rate tym dekh lena kya hai. Aisa hi 100 waat ka bulb 10 ghante mai ek unit consume krega. Aur 9 waat ka tum nikal lena. Chalo tumhara ye chapter to kahatam hua ab kal 9th class ka structure of atom dekhna hai. Agar baki chapters chahoye to comment kr dena. Aur web pr bhi comment hote hai)
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